Add get_frameworks_size lane in Fastfile

[nuno-vieira]

🔗 Issue Links

Relates to https://github.com/GetStream/ios-issues-tracking/issues/448

🎯 Goal

Add an easy way to get the SDK sizes. For now, it just shows the sizes in Megabytes. In the future, we can use bloaty to show the diffing between 2 binaries and show which files increased the most. We would also need to store the previous binary somewhere. Either way, it is out of the scope of this PR. This one is for us to have a way to manually check the SDK size more easily.

• [ ] I have signed the Stream CLA (required)
• [ ] This change follows zero ⚠️ policy (required)
• [x] This change should be manually QAed
• [ ] Changelog is updated with client-facing changes
• [ ] New code is covered by unit tests
• [ ] Comparison screenshots added for visual changes
• [ ] Affected documentation updated (docusaurus, tutorial, CMS)